Received: 28 August 2018
Accepted: 8 March 2019
First Online: 2 April 2019
Ethics approval and consent to participate
: Ethical approval was not obtained as the manuscript was based on aggregated data from the surveillance system and did not report any individual human subject information. However, the authors sought concurrence for publication of this work from the Sierra Leone Ministry of health and Sanitation.
: Not applicable.
: The authors declare that they have no competing interests.
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